1. Field of the Invention
The invention is based on an electrical apparatus, in particular a surge arrestor.
2. Discussion of Background
The invention refers to a prior art of electrical apparatuses as is specified in EP 0 564 334 A1. An electrical apparatus which is described in this prior art and is preferably designed as a surge arrestor or as an insulator for high-voltage or medium-voltage grid systems, contains a detection and indicating apparatus which is used to monitor the electrical apparatus for a fault current. This apparatus has a dielectric housing with an easily frangible window. An electrical connection of the electrical apparatus is passed through the dielectric housing. The part of the electrical connection located in the housing interior is surrounded by a magnet core, which is fitted with the secondary winding of a current transformer that has the electrical connection as the primary winding. The secondary winding is connected to a non-reactive resistor which is embedded in an explosive charge that is arranged in the housing interior. When a fault current occurs, the non-reactive resistor, which is continuously fed with current from the current transformer, is heated very severely. The resistor detonates the explosive charge above a critical limiting temperature. The window of the dielectric housing is in consequence broken open and a colored ribbon, which is used as an indicating element, is ejected from the housing. After tripping and optical signaling of the fault state, the electrical apparatus and the detection and indicating apparatus are removed and replaced.